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how to
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i have a feild where the user must insert only integer values not chars..if they insert a char an error messege should appear..how can i do this and what is the code to do it
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Join Date: Aug 2005
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You can test this using a loop which goes through the numbers:
If this condition is valid then proceed to the next part of the program. For this you can use a key listener.
"0123456789"If this condition is valid then proceed to the next part of the program. For this you can use a key listener.
Last edited by iamthwee; Aug 3rd, 2006 at 9:40 am.
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actually how do i write the code..i dont know anything abt keylister i am a newbie for java
can u give me a sample code
can u give me a sample code
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Join Date: Aug 2005
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Solved Threads: 377
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Originally Posted by shapeshifter
actually how do i write the code..i dont know anything abt keylister i am a newbie for java
can u give me a sample code
KeyView.java
Java Syntax (Toggle Plain Text)
Or you could wait till the user enters the entire expression and parse it at the end?
Last edited by iamthwee; Aug 4th, 2006 at 12:31 pm.
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hai, check this code and hope this helps u.
/*in ur main program where u have ur textfield, declare the TextField as follows*/
JTextField txtInput =username = new JTextField(new FixedNumericDocument(4,true),"",15);
/*where 4 is the maximum number of digits that is allowed, boolean true denotes whether u need the text box to accept only integers and false otherwise, and 15 is the size of the text field.*/
/* Then as a seperate class call the following code*/
///////FixedNumericDocument.java////////
import javax.swing.*;
import javax.swing.text.*;
import java.awt.*;
public class FixedNumericDocument extends PlainDocument {
private int maxLength = 9999;
private boolean numericOnly;
public FixedNumericDocument(int maxLength, boolean numericOnly) {
super();
this.maxLength = maxLength;
this.numericOnly = numericOnly;
}
//this is where we'll control all input to our document.
//If the text that is being entered passes our criteria, then we'll just call
//super.insertString(...)
public void insertString(int offset, String str, AttributeSet attr) throws BadLocationException {
if (getLength() + str.length() > maxLength) {
Toolkit.getDefaultToolkit().beep();
return;
}
else {
try {
if (numericOnly) {
//check if str is numeric only
Integer.parseInt(str);
//if we get here then str contains only numbers
//so it's ok to insert
}
super.insertString(offset, str, attr);
}
catch(NumberFormatException exp) {
Toolkit.getDefaultToolkit().beep();
return;
}
}
return;
}
}
/*in ur main program where u have ur textfield, declare the TextField as follows*/
JTextField txtInput =username = new JTextField(new FixedNumericDocument(4,true),"",15);
/*where 4 is the maximum number of digits that is allowed, boolean true denotes whether u need the text box to accept only integers and false otherwise, and 15 is the size of the text field.*/
/* Then as a seperate class call the following code*/
///////FixedNumericDocument.java////////
import javax.swing.*;
import javax.swing.text.*;
import java.awt.*;
public class FixedNumericDocument extends PlainDocument {
private int maxLength = 9999;
private boolean numericOnly;
public FixedNumericDocument(int maxLength, boolean numericOnly) {
super();
this.maxLength = maxLength;
this.numericOnly = numericOnly;
}
//this is where we'll control all input to our document.
//If the text that is being entered passes our criteria, then we'll just call
//super.insertString(...)
public void insertString(int offset, String str, AttributeSet attr) throws BadLocationException {
if (getLength() + str.length() > maxLength) {
Toolkit.getDefaultToolkit().beep();
return;
}
else {
try {
if (numericOnly) {
//check if str is numeric only
Integer.parseInt(str);
//if we get here then str contains only numbers
//so it's ok to insert
}
super.insertString(offset, str, attr);
}
catch(NumberFormatException exp) {
Toolkit.getDefaultToolkit().beep();
return;
}
}
return;
}
}
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